The Plan Your Own Party Kit is a kit for throwing fun parties. It only appears in the episode "Party Pooper Pants."
Inside the kit contains a list of Bikini Bottomites to invite to the party, an instruction manual, and some party supplies (balloons, noise makers, etc.)
Barg'N-Mart sells these kits in a party-themed box which is turquoise on the front side and yellow on the middle, both of which depict colorful balloons and streamers. The boxes they're sold in also contain a white "sale tag" on the front and a red shell with streamers on the back as well as yellow, blue, and green balloons on said shell.
Role in episode
SpongeBob is planning a special house party for the night and needs the best ideas on how to host it. As a result, he stops by Barg'N-Mart to buy a Plan Your Own Party Kit, which the storekeeper, Lou, offers SpongeBob for free if he promises to leave the store and get out of his hair, which SpongeBob does.
Afterwards, he is at his house, planning the party by taking the advice the kit offers him. SpongeBob expects the party to be a blast. Unfortunately, it later turns out not to be (at least not for him), as the guests don't follow the routine of activities in order.
The kit's ignorance of the police leads SpongeBob to arrest the same night; Officer John Slugfish and Nancy catch him in a bunny outfit, attempting to break into his house as a result of being locked out. The two policefish accuse him of attempted burglary. However, SpongeBob informs them that he lives there and that he's throwing a party, which leads the two cops to asking why they weren't invited. SpongeBob answers them by saying that the Plan Your Own Party Kit didn't mention the police, which results in him staying behind bars for the rest of the night.